From: Bartosz Golaszewski Date: Sun, 17 Jul 2016 18:40:06 +0000 (+0200) Subject: eeprom: at24: tweak the loop_until_timeout() macro X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=24da3cc0e25f48e12656226e5ed313573a3b443f;p=linux-beck.git eeprom: at24: tweak the loop_until_timeout() macro loop_until_timeout() replaced a do {} while loop in the at24 driver with a for loop which, under certain circumstances (such as heavy load or low value of the write_timeout argument), can lead to the code in the loop never being executed. Make sure that at least one iteration of the code enclosed within loop_until_timeout() is always executed. Suggested-by: Wolfram Sang Signed-off-by: Bartosz Golaszewski Signed-off-by: Wolfram Sang --- diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index 04e91e331fc5..3cdf8e1ca0ad 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -116,7 +116,8 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)"); /* * Both reads and writes fail if the previous write didn't complete yet. This * macro loops a few times waiting at least long enough for one entire page - * write to work. + * write to work while making sure that at least one iteration is run before + * checking the break condition. * * It takes two parameters: a variable in which the future timeout in jiffies * will be stored and a temporary variable holding the time of the last @@ -124,9 +125,8 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)"); * holding at least 32 bits. */ #define loop_until_timeout(tout, op_time) \ - for (tout = jiffies + msecs_to_jiffies(write_timeout), \ - op_time = jiffies; \ - time_before(op_time, tout); \ + for (tout = jiffies + msecs_to_jiffies(write_timeout), op_time = 0; \ + op_time ? time_before(op_time, tout) : true; \ usleep_range(1000, 1500), op_time = jiffies) static const struct i2c_device_id at24_ids[] = {